7 LAYERS

Provides an interface to the end-user

Handles network security and architecture-independent data formats

Coupled to transmission medium; Examples: Router, Modem

Handles crash recovery

Translates and manages message communication through sub-network

Connects two systems at the same layer; Example: Bridge

Responsible for connection negotiation

Manages end-to-end control

A coordinated set of guidelines that describe a communications environment

Translates and manages message communication through sub-network